In a conventional pipe coupling, a female coupling member and a male coupling member, when coupled together, are held with a locking element so as not to detach from each other. Accordingly, when excessive tensile force is, for some reason, applied to piping connected to the pipe coupling, the piping or a device connected to the piping, for example, may be broken, which may cause an unexpected accident. To prevent such an accident, there have been developed emergency detachable pipe couplings (Japanese Utility Model Registration Application Publication No. Hei 7-35893 and Japanese Patent No. 5,570,494 configured such that when an external force of a magnitude greater than a given magnitude is applied in a direction in which a female coupling member and a male coupling member are forced to separate from each other, the female and male coupling members detach from each other, thereby preventing breakage of the piping and so forth.
The above-described conventional emergency detachable pipe coupling is disadvantageous as will now be explained. When an external force of a magnitude greater than a given magnitude acts on the female coupling member and the male coupling member in the longitudinal axis direction of the pipe coupling, the female and male coupling members are detached from each other. However, when pipings which are connected to the female and male coupling members, respectively, are bent relative to each other and hence high bending stress is applied to the pipings and the pipe coupling, for example, even if the bending stress is so high that the pipings or the pipe coupling may be broken, the force acting on the pipe coupling in the tensile direction along the longitudinal axis direction may not be so great, so that the pipe coupling may fail to be decoupled.